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L. H. COOLiDGE PROPELLER BLADE MEASURING INSTRUMENT Filed Dee. a, 1925 INVENTDR lfiilgd lf fiaa/i afye ATTORNEY" Patented Dec. 25-, 1928.

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Application filed December 9.19%. Serial a. 14,250.

This invention relates to an instrument for measuring helical surfaces and, more, espe- .cially, the surfaces "of propeller blades for the purpose of a'scertainingthe helical pitch thereof.

. The object of the inventlon, generally, 18 to provide an instrument'of this character which 18 adapted to be conveniently employed to ace invention consists'in the novel con-' struction, adaptation and combination of parts hereinafter described and claimed.

. to a propellenparts of the devices for scour Fig. 1. Fig. 3 is a vertical section taken" through the carriage and the beam, with the In the accompanying drawing,--

Figure 1 is a front elevation of an instru meat embodying my inventionshown applied ing the instrument to the propeller and a portion of the latter being in section. Fig. 2 1s a horizontal section taken on the line 2--2 of slide shown in si elevation. Fig. 4 isavertical section. taken substantially on line 4-4; of Fig. 5. Fig. 5 is a horizontal section on line 5-5 of Fig. .1. Fig. 6 is a front elevation illustrating parts of the invention shown in Fig. 1 to a larger scale.

-' clamping nut 14. which is I In said drawing, the reference numeral 10 represents a cylindrical post rovided with a rigid collarll of a conoid shape, and a screw threaded stem 12 in axial alignment with each other. Mounted for axial adjustment upon said stem is a second conoidal collar 13, and a threaded upon the stem.

The colloidal collars 11' and 13 "are arranged, as shown in Fig. 1, with their smaller ends in opposed relation with each other so that they may enter the ends of the bore A of the threaded stem and appear in the'following debeam is allel ri s 8 d ng edges ribs-27 whic attaching the blocks to a bow-sha a propeller hub H for the purpose of centering the stem in such bore and cooperate with the clam ing nut to couple the post 10 with the pro ali nment with each other.

. ounted'upon said post for vertical and rotaxy movements is a clamp collar 15 provide with apertured ears 16 for a'screw bolt 17 which is secured in the aperture of one of said ears and extends through the aperture of the other ear to receive a nut 18 whereby the collar 15 is rigidly clamped to the post in a selected position. .In its upper portion said clamp collar is provided with a peri 2) of a predetermm arcuate len circumferentially of the collar. Fitted or rotative movement to the 'st 10 and supported b said clamp collar lb a sleeve 20. constitu y the hub of a'horizontalarm or beam 21. j Sai provided in its front face with a cess 22 Fig. 3) disposed-between two for 10 "tudinall o beam and having front w l y radially of said post.

The extent of the however, of the beam clamp collar 15 'is limited, preferably to thirtysix' degrees circular measure, that is aces24inap1ane revoluble movement,

heral groove 19 (Fig ler in axial with respect to the i to say to one-tenth of a complete revolution.

To e ect such relatively limited movement,

the beam hub is provided with a de ding In 25 which is arranged to exten i rlto the col ar groo uate-lengt less than that of the sufficient to rmit such horizo ta vibratory movement 0 the beam. p Positioned within the recess 22o! 21 and movable lon 'tudinally thereofis a carriage 26 havinglalb true in guldeways 28 of ve-19, said lug being ofaan arc ve just ngiits upper and lower the beam. Said carriage is secured in adjusted positions to the beam by suitable means, the means shown comprising brake blocks 29 the carriage and yield operatin in slots 30 o ingly held in engagement with the beam by resilient spreader 31. To disengage said locks from the beam, said spreader is flexed as by means" of a manuall actuated headed bolt 32 slide ably mounte in a boss 33 of the'carriage.

Rigid with said and constituting a part thereof is a vertically disposed guide BOX 34, preferably of rectangular shape in horizontal section (Fig. said guide box being provided in its front, for its entire length with a central slot 35. v

The inner surface 36 of back wall of said guide box is dis sed in a plane with the front surfaces 24 of t ebeam ribs 23.

Fitted within the guide box 34 for vertical movement is a hollow bar 37 having, throughout its length at itsfront, a rib 38, of a subin a point 40.

stantially T-shape in horizontal section,said rib extendin lengthwise through the slot 35 of the ide ox. Socketed in the lower end of the ar 37 is an extension 39 terminating The point 40 and the back surface 41 of the bar 37 are at all times retained by the guide box 34 in a vertical plane coextensive with the plane of the front surfaces 24 of the beam ribs and therefore in a plane coincident with the axis of the beams revolution. The above mentioned bar 37 with its rib 38 and the extension 39 will, as a whole, be hereinafter designated as the slide and is designated in its entirety by the letter S.

Provided within the slot 35 of the guide box 34 and mounted upon the T-shaped rib 38 of said slide is a block 42 hereinafter termed the runner.

' Said'runner is fitted to the rib 8to afford frictional-engagement therewith sufficient to cause the runner to be moved up and down in unison-with the slide as the latter is moved vertically in the guide box; yet permitting the runner tobe moved with respect to the slide for the purpose of adjustment as will be resently explained.

s best illustrated in Fig. 6, on the front of the guide box 34 at opposite sides of the slot 35 are produced scales 43 and 44 which, in this instance, read in tenths of inches, the scale 43 at one side of said slot commencing at a zero mark 0 (Fig. 1) near the upper end of the guide box, and the scale 44 at the other side commencing near theupper end of the guide box with-a predetermined mark, as for I example, included in the scale'43 near its lower-end.

The runner is provided with an index mark 45 'extendingtransversely thereacross and in association therewith, at each side of the runner is a Vernier 46 for cooperating with the aforesaid scalesfortakingfofi subdivi-.

blade, as B, in proximity to the opposite sides of the blade. In thus swinging the beam from side to side the beam lug 25 encounters the end walls 19 and 19 (Fig. 2) of the groove 19 of the clamp collar to adjust the same into a suitable rotary position, whereupon the clamp collar is rigidly secured by means of the bolt 17 and nut 18 to the post 10.

The carriage 26 carrying the slide S, is then shifted lengthwise of the beam 21 to position the slide at a selected distance radially from the hub axis, which distance is conveniently found by means of an indicating mark 47 on the carriage registering with a desired denominating mark of a scale 48 which is readable in inches and fractions thereof, provided on the beam 21.

The operator now takes hold of the slide S with one hand and the beam 21 with his other hand and thereby moves the slide. and beam vertically and horizontally, respectively, to cause the point 40 of the slide to contact with a place, as at m, for example, on the high side of the propellerblade as determined by the beam lug 25 encountering the groove wall 19 of the clamp collar 15. Thus arranged, the slide is by one of the operatorshands held firml against the blade and with his other han he elevates the runner 42 until the index mark 45 thereon is brought to the Zero mark 0 of the scale 43. The beam is then swung to carry the lug 25 thereof against the wall 19 at the other end of the collar groove 19 and, where the beam is thus stopped, the

operator lowers the slide until the point thereof contacts with the blade, as at mi. It is to be understood that the runner 42 is carried down with the slide, consequently the index mark, or a Vernier on the runner will indicate bya direct reading with respect to the carriage scale 43 the vertical movement of the slide at the extremities of an arc of 36, hence the scale of tenths will rovide the actual length of pitch of the bla e B at the circumference of a circle whose radius is the distance, denoted on the beam scale 48, of the; slide point 40 from its axis of revolution-that is from the center of the pro eller. This function of the instrument may e expressed as follows: As 36, the revoluble movement of the point 40, is to 360 in a circle; so is the reading u on the scale 43, in tenths of inches, to the he ical pitch in actual inches. g

In the event that-the len h of the scale 43 is insuflicient to accommo ate the diiference in the heights of the runner for complementary measures of the blade, the second scale 44 is usuable supplementary to the first scale 43 in the following described manner, to wit: When the runners index mark meets a mark, as M, located near the lower end of the scale-43, the slide is held in its then lowered position by the operator while the operator moves the runner upwardly upon the slide until its index mark coincides with y a mark, as M on the scale 44 having a denomination, as 60 for example, which will correspond with the mark denoted by M on scale 43. Being thus stepped up, so to s the runner is again lowered with the slide until both are stopped by the slide point coming into contact w th the blade, the totaldistance which the slide makes in its successive downward movements beingindicated b the runner with respect to the scale 44-. e use of two supplementary scales, however, 'is for compactness only, as a-continuous scale will answer the same purpose and may even prove more expeditious and convenient where the v instrument is confined for use in a single do not wish to be understood as 1 invention to such use only, inasmuch as it may be employed for measuring other devices, for example, the helical blade of a screw-conveyor. Furthermore I do not confine myself to the specific construction shown eircept as limited by the of the following e um. I v I What I claim, is,--

In an instrument for measuring the pitch of a propeller blade, the combination with a post ada ted to be secured axially to a propeller hu a beam connected to said post for a predetermined arouate movement, said beam being provided in its front face with a recess between two ridges disposed longitudinally of the beam, a carriage positioned in the recess of said beam and connected to the latter for movement radial of said post, a spring actuated clutch comprising two brake blocks engageable with the ribs of said beam for securmg said carria e at selected positions to said beam, and a slid movement at right angles to said beam, said carriage being provided with a scale of marks, and a runner slidably connected to said slide for movement at ri ht'angles to said'beam with and .indepen ently of the slide, said runner being provided with a mark adapted to be used in cooperation with the scale marks on the carriage for regulating the relative positions of the slide with respect e mounted in the carriage for to the carriage.

Signed at eatt1e,Washington, this 3rd day 

